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User's Guide

SLMU002–June 2011

DRV882x Evaluation Modules

This user guide is provided as a supplement to the DRV8828 and DRV8829 product data sheets. It details

the hardware implementation of the CPG006_DRV882xEVM Customer Evaluation Module (EVM). This

EVM is an evaluation board for the DRV8828 and DRV8829 motor controller devices.

This document covers the operation of the DRV8828EVM and the DRV8829EVM, collectively identified as

DRV882xEVM. The EVM contains both a pair of DRV882x devices and a customer programming board

(CPG006). Throughout this document, the abbreviations CPG006, EVM, and the term evaluation module

are synonymous with the CPG006_DRV882xEVM. Unless otherwise indicated, all references to device

operation apply to both devices.

Contents

1 Introduction .................................................................................................................. 2

2 Block Diagram ............................................................................................................... 2

3 Installing Drivers and Software ............................................................................................ 6

4 UART Mode .................................................................................................................. 6

5 Internal Indexer Mode ..................................................................................................... 14

6 Schematics ................................................................................................................. 14

List of Figures

1 DRV882xEVM Block Diagram............................................................................................. 2

2 DRV882xEVM Pin Configuration.......................................................................................... 3

3 Connectors................................................................................................................... 5

4 DRV882xEVM Software GUI: Startup Window ......................................................................... 7

5 Control Signals .............................................................................................................. 8

6 Current Regulation Control ................................................................................................ 9

7 Stepper Control Screen .................................................................................................... 9

8 Acceleration Profile........................................................................................................ 11

9 Decay Mode................................................................................................................ 12

10 Move Steps................................................................................................................. 13

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SLMU002–June 2011 DRV882x Evaluation Modules

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Summary of content (19 pages)

PAGE 1
User's Guide SLMU002 – June 2011 DRV882x Evaluation Modules This user guide is provided as a supplement to the DRV8828 and DRV8829 product data sheets. It details the hardware implementation of the CPG006_DRV882xEVM Customer Evaluation Module (EVM). This EVM is an evaluation board for the DRV8828 and DRV8829 motor controller devices. This document covers the operation of the DRV8828EVM and the DRV8829EVM, collectively identified as DRV882xEVM.
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Introduction 1 www.ti.com Introduction The CPG006_DRV882xEVM is an evaluation platform populated with two DRV8828PWP or two DRV8829PWP single H-Bridge power stage controllers. These devices have been optimized to drive bipolar stepper motors; therefore, two devices are required. The CPG006 also contains an MSP430 microcontroller and an USB interface chip.
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Block Diagram www.ti.com 2.1 Power Connectors The CPG006 offers access to the motor voltage (VM) power rail via terminal block J4. A set of test clips in parallel with the terminal block allows for the monitoring of the input power rail. The user must apply VM power according to the recommended product data sheet parameters. For the DRV8828, the product data sheet is literature number SLVSA11. For the DRV8829, the product data sheet is SLVSA74.
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Block Diagram 2.3 www.ti.com Jumpers This EVM has no jumpers that must be configured by the user. 2.4 Switches Switch S1 offers EVM configurability by moving each individual switch, as listed in Table 1. Table 1.
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Block Diagram www.ti.com Figure 3 shows the two connectors and the respective signals for each. J11 J10 USM0 GND USM1 ENABLE STEPPER USM2 DIRECTION nRESET STEP nSLEEP RESET INDEX GND 3.3 V Figure 3. Connectors USMx: Refer to Table 1 and Table 2 for details on operation. nRESET: Same as nRESET on the DRV882x device. A LO on this signal places the device into reset with the H Bridges 3-stated. Refer to the respective device data sheet for further information about the nRESET signal.
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Installing Drivers and Software 2.6 www.ti.com Potentiometer R19 The microcontroller digital-to-analog converter (DAC) outputs are referenced from an external reference voltage that is derived from the internal 2.5-V reference voltage. A potentiometer (R19) is provided to scale the analog reference voltage to be used by the DAC12 module. This voltage scaling offers a direct means to scale the microstepping current magnitude from 0 A to a 5-A sine wave peak, depending on the EVM module.
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UART Mode www.ti.com Figure 4. DRV882xEVM Software GUI: Startup Window All the control signals required to control the motor enablement (ENABLE or INx), the direction of rotation (PHASE or the respective combination of the INx pins), current control (through VREF) and PWM control for both enablement and direction control signals are available. Access to the DAC responsible for generating the VREF analog voltage is achieved by moving a simple slider (see Figure 6).
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UART Mode www.ti.com Once the application has initialized and started up, the order of events should be: • Press Connect. If COM ports are available, the application searches for the EVM. If no EVM is found, an error message notifies the user. If the port is available and communications are successful, the menu item changes from Connect to Disconnect. Press Disconnect if you want to disable serial communications. • Verify successful communication.
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UART Mode www.ti.com 4.3 Updating DAC Output for Current Control (VREF) During evaluation, the user may want to study the operation of the ITRIP regulation scheme. Both MSP430F2617 MCU DAC channels can be controlled through the provided sliders, shown in Figure 6. Moving these sliders produces the effect of having the regulated current be directly proportional to the slider position.
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UART Mode www.ti.com This screen is an area that offers access to a series of simple stepper control algorithms. The user can control motor enablement, rotation rate, direction of rotation, current decay mode during microstepping, microstepping resolution (from full step to 512 degrees of microstepping), and the number of steps the motor should move. Motor motion can only occur by using an acceleration profile.
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UART Mode www.ti.com Desired Speed PPS Time Base Accel Rate Start Speed PPS Start Speed PPS Figure 8. Acceleration Profile The following controls are available within the Motor Control Frame: Start Speed PPS: Number of pulses per second (or Full Steps Per Second) at which the motor will rotate at the beginning of operation. The SW will only allow a number as small as 61 PPS and can be taken to a number as large as 65535 PPS.
PAGE 12
UART Mode www.ti.com As a result, we will want to use slow decay during most of the time, with the exception being those periods of the microstepping cycle in which waveform generation is compromised. This translates to the usage of slow decay mode while the winding current is charging (Quadrants 1 and 3 as seen in Figure 9) and fast decay mode during while the winding current is discharging (Quadrants 2 and 4 as seen in Figure 9).
PAGE 13
UART Mode www.ti.com Since in a previous application note (SLVA416) we implemented 256 degrees for a microstepping engine, we can take this design one step further. The DRV8828EVM and DRV8829EVM have been programmed to divide a full step to up to 512 degrees of microstepping. The microstepping resolution frame gives the user the option to change the full step divider factor so that microsteps from half step to 512 degrees of microstepping are obtained.
PAGE 14
Internal Indexer Mode www.ti.com On the CPG006 board, the algorithm to compute acceleration, steady state, and deceleration is an hybrid of two functions: How fast we are modifying the stepping rate so that a desired speed is reached and how many steps we have allocated to modify said rate. This translates to two mechanisms on terminating the acceleration profile. Either acceleration/deceleration culminates as we reach the desired/start speed, or as the allocated number of steps elapses.
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Schematics www.ti.com 4 VM J1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 A 3 CP1_A CP2_A VCP_A AOUT1_28 ISNSA_28 AOUT2_28 AOUT2_28 ISNSA_28 AOUT1_28 VM AVREF AVREF VM C4 C7 0.1uF CP2_A VCP_A 0.1uF R3 0.2 C8 5 REG3P3 U2 0.01uFCP1_A C2 AOUT1_28 ISNSA_28 AOUT2_28 AOUT2_28 ISNSA_28 AOUT1_28 AVREF 0.
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Schematics www.ti.com 1 2 3 4 5 6 REG3P3 S2 C19 J9 PWRSelect 0.1uF GND DAC_AVREF GND 0.1uF 28 27 26 25 24 23 22 21 20 19 18 17 16 15 OSCO OSCI A CBUS0 CBUS1 RESET USBDM USBDP C3 0.1uF R16 5.1K GND C21 0.1uF U5 DAC_BVREF C22 GND 1 2 10uF 3 4 DAC_AVREF5 DAC_BVREF6 7 8 9 10 11 12 USM0 13 C28 USM1 14 USM2 15 16 33pF GND Y1 2 R19 C27 5K 33pF 1 8 MHZ DVCC P6.3/A3 P6.4/A4 P6.5/A5 P6.6/A6/DAC0 P6.7/A7/DAC1/SVSIN VREF+ XIN XOUT VeREF+ VREF-/VeREFP1.0/TACLK P1.1/TA0 P1.2/TA1 P1.
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Schematics www.ti.com 1 2 3 4 C13 0.1uF 100uF C18 61.9K 3 4 VM 10uF R11 FB NC NC NC GND 39K EN GND TP3 1 D1 C14 2 8 GND TP6 GND GND 7 6 5 VM TPS79801 B V3P3 GND TP4 TP2 GND TP5 1 VM R10 1 2 IN 0 R6 3.
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Evaluation Board/Kit Important Notice Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards.
PAGE 19
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.